Author: Dirk-Jan

Last week I acquired a new modem because the old one supplied by the provider was acting strange and I wanted it. The new modem is a Cisco 887VA router equipped with a VDSL2/ADSL2+ interface so that it could replace the previous Fritz!box. A day after I had finished the setup I noticed some unusual things which eventually led to the conclusion that packet fragmentation was occurring. In my search for an answer I learned that the Point-to-Point protocol (PPP) needs 8 bits which need to be subtracted from the default MTU of 1500. So configuring an MTU size of 1492 for the Dialer0 interface and altering the max segment size ‘ip tcp adjust-mss 1452’ on the internal VLAN interface did the trick.

But, then I stumbled upon a service page of my provider stating (in Dutch):

Some months ago I decided it was time to secure my steadily growing MySensors network. As described on the MySensors website this can be implemented by using a software or hardware solution to sign messages. I chose the hardware solution using the ATSHA204A component. Because the more convenient break-out board was out of stock, I ordered a little strip of 3-legged ATSHA204A surface mounted devices (SMD). But when they arrived I was struck by the size of those things.

Feeling steady handed today I took the nerve to solder one of them to put on my gateway device. This gateway device consists of a Arduino Uno, Ethernet shield (W5100) and nRF24L01+ PA/LNA. There are some nodes (Sensebender Micro) in the house which are already equipped with an ATSHA204A.

Somewhat proud of my accomplishment I like to share some picture of what it looks like.

Curious and want to know more about securing MySensors, check out the following page.